1. Field of the Invention
The present invention relates to an inner-rotor motor.
2. Description of the Related Art
In recent years, a variety of demands have been raised regarding inner-rotor motors. Examples of such demands include carrying out direct-current drive using an alternating-current power supply, carrying out stepping control, and improving rotational accuracy by using an encoder. In order to fulfill the demands as described above, it is necessary to mount a large number of electronic components on a circuit board. Meanwhile, in the case of an inner-rotor motor, it is structurally necessary to accommodate the circuit board inside the motor. This makes it difficult to increase the size of the circuit board.
Aside from the above, motors of the above type are used in applications, such as household electrical appliances, IT equipment, and industrial equipment, where miniaturization is demanded. Inner-rotor motors installed in such devices are also required to be reduced in size and thickness. In some applications, a demand for reductions in size and thickness of the motors needs to be fulfilled even though there is not a demand concerning control. That is, there is a problem in that it is impossible to increase the size of the circuit board.
According to a technique described in JP-A 2007-135357, a plurality of small holes are defined in a printed circuit portion of a control circuit board 9, and one end portion 10a of a conductor wire 10 is inserted through one of the small holes to project above a surface of the control circuit board 9 to an appropriate extent. One end portion of a winding 5 of a stator 2 is wound around the projecting portion, the projecting portion is bent about 90 degrees to extend along the surface of the control circuit board 9, and the end portion of the winding 5 is soldered and thus fixed to the projecting portion. Another end portion 10c of the conductor wire 10 is inserted through another one of the small holes, and the other end portion 10c is soldered and thus fixed to the printed circuit portion of the control circuit board 9.
JP-A 2007-166851 discloses a technique of soldering a lead wire terminal 5 of a stator winding to a land 6 on a rear side of a board 3. A cut 7 is defined in an outer circumference of the board 3, the lead wire terminal 5 is held and fixed at the cut 7, and a portion of the lead wire terminal 5 extending below the rear side of the board 3 is soldered and connected to the land 6 on the rear side of the board 3.
However, the technique described in JP-A 2007-135357 has a problem in that it is necessary to define the plurality of small holes in the printed circuit portion, and that, when a plurality of end portions of windings are soldered, a mounting space on the control circuit board is correspondingly reduced.
Meanwhile, a motor described in JP-A 2007-166851 has a problem in that the board is fixed on an upper side of a bracket, and this leads to an increased size of the motor.